From ee278edc8f2cc998f24aa12fede88a4c9479a9a5 Mon Sep 17 00:00:00 2001
From: peyman <peymanahmadifar@gmail.com>
Date: Thu, 9 Oct 2025 14:11:21 +0330
Subject: [PATCH 1/2] Add option to exclude reverse relations from model diffs

Add AUDITLOG_EXCLUDE_REVERSE_RELATIONS setting which, when True,
excludes auto-created reverse relation fields (auto_created and not concrete)
from the diff calculation to avoid extra DB hits and inadvertent mutation
of instance._state.fields_cache.

Closes #551 (or: Fixes behavior described in jazzband/django-auditlog#551).
---
 auditlog/conf.py      |  5 +++++
 auditlog/diff.py      | 10 ++++++++++
 docs/source/usage.rst | 10 ++++++++++
 3 files changed, 25 insertions(+)

diff --git a/auditlog/conf.py b/auditlog/conf.py
index b151b24..254ecd0 100644
--- a/auditlog/conf.py
+++ b/auditlog/conf.py
@@ -21,6 +21,11 @@ settings.AUDITLOG_EXCLUDE_TRACKING_FIELDS = getattr(
     settings, "AUDITLOG_EXCLUDE_TRACKING_FIELDS", ()
 )
 
+# Exclude reverse relation fields across all models
+settings.AUDITLOG_EXCLUDE_REVERSE_RELATIONS = getattr(
+    settings, "AUDITLOG_EXCLUDE_REVERSE_RELATIONS", False
+)
+
 # Mask named fields across all models
 settings.AUDITLOG_MASK_TRACKING_FIELDS = getattr(
     settings, "AUDITLOG_MASK_TRACKING_FIELDS", ()
diff --git a/auditlog/diff.py b/auditlog/diff.py
index fc98987..a45c38c 100644
--- a/auditlog/diff.py
+++ b/auditlog/diff.py
@@ -213,6 +213,16 @@ def model_instance_diff(
         fields = set()
         model_fields = None
 
+    # Optionally exclude reverse relations (auto-created fields).
+    # Reverse relations (auto_created & not concrete) can cause unwanted DB hits
+    # and mutate instance._state.fields_cache as a side-effect.
+    # Make this behavior opt-in via AUDITLOG_EXCLUDE_REVERSE_RELATIONS.
+    if settings.AUDITLOG_EXCLUDE_REVERSE_RELATIONS:
+        def is_reverse_field(f):
+            return getattr(f, "auto_created", False) and not getattr(f, "concrete", False)
+
+        fields = {f for f in fields if not is_reverse_field(f)}
+
     if fields_to_check:
         fields = {
             field
diff --git a/docs/source/usage.rst b/docs/source/usage.rst
index 4f9dda6..148a4ac 100644
--- a/docs/source/usage.rst
+++ b/docs/source/usage.rst
@@ -574,3 +574,13 @@ The mixin provides the following configuration options:
 - ``auditlog_history_template``: Template to use for rendering the history page (default: ``auditlog/object_history.html``)
 - ``auditlog_history_per_page``: Number of log entries to display per page (default: 10)
 
+.. versionadded:: 3.2.2
+
+Default: False
+
+Use ``AUDITLOG_EXCLUDE_REVERSE_RELATIONS`` to exclude reverse relation fields (auto-created fields
+where `field.auto_created is True` and `field.concrete is False`) when computing
+model diffs. This avoids accidental database queries for related objects and avoids
+mutating `instance._state.fields_cache` as a side-effect.
+
+Added to address: https://github.com/jazzband/django-auditlog/issues/551

From 952924f4cf0c9303faa3cf7955737a9f56db45aa Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 9 Oct 2025 10:45:55 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 auditlog/diff.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/auditlog/diff.py b/auditlog/diff.py
index a45c38c..a69465c 100644
--- a/auditlog/diff.py
+++ b/auditlog/diff.py
@@ -218,8 +218,11 @@ def model_instance_diff(
     # and mutate instance._state.fields_cache as a side-effect.
     # Make this behavior opt-in via AUDITLOG_EXCLUDE_REVERSE_RELATIONS.
     if settings.AUDITLOG_EXCLUDE_REVERSE_RELATIONS:
+
         def is_reverse_field(f):
-            return getattr(f, "auto_created", False) and not getattr(f, "concrete", False)
+            return getattr(f, "auto_created", False) and not getattr(
+                f, "concrete", False
+            )
 
         fields = {f for f in fields if not is_reverse_field(f)}